Sarah-Jeanne Salvy

Effect of Peers and Friends on Youth Physical Activity and Motivation to be Physically Active

OBJECTIVE To test whether the presence of a peer or a friend increases the motivation to be physically active in overweight and non-overweight youth in a laboratory setting. METHODS Youth motivation to be physically active as a function of the social context was measured using a computerized relative reinforcing value task to earn points exchangeable for physical and/or sedentary activities. RESULTS The presence of a friend (p<.001) increased youths; motivation to be physically active. The presence of a peer increased overweight youths; motivation to be physically active, whereas this was not the case for lean youth (p=.47). Participants biked a greater distance in the presence of a friend than when alone (p<.001). Overweight youth biked a greater distance in the presence of a peer than when alone, while this was not the case for lean youth (p=.23). CONCLUSIONS Friendships may increase youths motivation to engage in physical activity and promote greater physical activity in non-overweight and overweight youth.

Effects of social contexts on overweight and normal-weight children's food intake.

This study investigates the effects of peer influence on the food intake of overweight and normal-weight children. A mixed factorial design was employed, with childrens weight status (overweight vs. normal-weight) as a between-subjects factor, and social context (alone vs. group) as a within-subjects factor. A total of 32 children (n=17 overweight and n=15 normal-weight) between the ages of 6-10 years participated in this study. Findings from the random regression model indicated that overweight children ate more when with others than when alone, while in contrast normal-weight ate more with others than they did when alone. Therefore, social context differentially impacts the eating behavior of overweight and normal-weight children. This study underscores differences in responses to the social environment between overweight and non-overweight youths, and suggests that social involvement may be an important tool in treatment and prevention programs for overweight and obesity.

The effect of simulated ostracism on physical activity behavior in children.

OBJECTIVES: To assess the effects of simulated ostracism on children’s physical activity behavior, time allocated to sedentary behavior, and liking of physical activity. METHODS: Nineteen children (11 boys, 8 girls; age 11.7 ± 1.3 years) completed 2 experimental sessions. During each session, children played a virtual ball-toss computer game (Cyberball). In one session, children played Cyberball and experienced ostracism; in the other session, they were exposed to the inclusion/control condition. The order of conditions was randomized. After playing Cyberball, children were taken to a gymnasium where they had free-choice access to physical and sedentary activities for 30 minutes. Children could participate in the activities, in any pattern they chose, for the entire period. Physical activity during the free-choice period was assessed via accelerometery and sedentary time via observation. Finally, children reported their liking for the activity session via a visual analog scale. RESULTS: Children accumulated 22% fewer (P < .01) accelerometer counts and 41% more (P < .04) minutes of sedentary activity in the ostracized condition (8.9e+4 ± 4.5e+4 counts, 11.1 ± 9.3 minutes) relative to the included condition (10.8e+4 ± 4.7e+4 counts, 7.9 ± 7.9 minutes). Liking (8.8 ± 1.5 cm included, 8.1 ± 1.9 cm ostracized) of the activity sessions was not significantly different (P > .10) between conditions. CONCLUSIONS: Simulated ostracism elicits decreased subsequent physical activity participation in children. Ostracism may contribute to children’s lack of physical activity.

Peer Influence and Physical Activity Behavior in Young Children: An Experimental Study

BACKGROUND There is evidence that the presence of a friend increases physical activity behavior in school-aged children (≥ 8 years old) and in young adolescents. Little is known about the developmental trajectory of the effects of peer influences on childrens physical activity. Therefore, we sought to test the effect of the presence versus absence of a friend on physical activity in young children (≤ 6 years old). METHODS Physical activity was assessed, via accelerometery, in 3- to 6-year-old children, during 2 social conditions: alone and in the presence of a friend. During each condition, children were taken to a gymnasium and had free access to physical and sedentary activities for 30 minutes. In one condition children were tested alone (solo play), whereas in the other they were tested in the presence of a friend who had access to the same activities. RESULTS Children exhibited 54% greater (P < .02) average accelerometer counts during the friend condition (mean = 2629, SD = 1080 or 5.7 METs) than during the solo play condition (mean = 1707, SD = 1009 or 4.5 METs). CONCLUSIONS The presence of a friend contributes to increased physical activity behavior in young children.

Influence of peers and friends on overweight/obese youths' physical activity.

This review offers a theoretical framework to account for the effects of peers on youths’ physical activity. Our research indicates the following: 1) that the youth are more physically active in the presence of friends and peers than in the presence of family members or when alone, 2) peers and friends increase overweight/obese youths’ motivation to be physically active, 3) peers’ weight status does not moderate the effect of peers on youths’ physical activity, and 4) experiencing negative peer interaction, such as ostracism, decreases physical activity in youth. We propose that the consideration of the peer social context as a contributor to physical (in)activity and maintenance of overweight status may further our understanding of physical and behavioral health trajectories and improve prevention and intervention efforts.

Wheel running produces conditioned food aversion

Previous investigations of conditioned taste aversion (CTA) induced by wheel running have used flavored liquids such as conditioned stimuli (CSs). Assuming that classical conditioning mediates activity anorexia, it is expected that CTA induced by physical activity should extend to food stimuli. The main purpose of the present experiment was to investigate this possibility. Rats were given a 60-min access to a running wheel [unconditioned stimulus (US)] either before or after being exposed to a novel distinctive flavored food (CS). An additional group had access to running wheels 4 h after receiving the CS food. Results from the present experiment indicate that regimented and contingent periods of wheel running decrease consumption of a food available before wheel running in nondeprived rats.

Taste avoidance induced by wheel running: effects of backward pairings and robustness of conditioned taste aversion.

Rats repeatedly exposed to a distinctive novel solution (conditioned stimulus, CS) followed by the opportunity to run in a wheel subsequently drink less of this solution. Investigations on this phenomenon indicate that wheel running is an effective unconditioned stimulus (US) for establishing conditioned taste aversion (CTA) when using a forward conditioning procedure (i.e., the US-wheel running follows the CS-taste). However, other studies show that wheel running produces reliable preference for a distinctive place when pairings are backward (i.e., the CS-location follows the US-wheel running). One possibility to account for these results is that rewarding aftereffects of wheel running conditioned preference to the CS. The main objective of the present study was to assess the effects of backward conditioning using wheel running as the US and a distinctive taste as the CS. In a between-groups design, two experimental groups [i.e., forward (FC) and backward conditioning (BC)] and two control groups [CS-taste alone (TA) and CS-US unpaired (UNP)] were compared. Results from this experiment indicated that there is less suppression of drinking when a CS-taste followed a bout of wheel running. In fact, rats in the BC group drank more of the paired solution than all the other groups.

Nutritional interventions for individuals with bulimia nervosa

Many physical and psychological effects of bulimia nervosa are caused by the patient’s partial starvation and chaotic nutritional cycle. Attention should thus be initially directed to correcting nutritional deficiencies and abnormal eating patterns, and providing dietary counselling. Nevertheless, very little has been written about the nutritional management of this eating disorder. Nutritional counselling for bulimia patients is reviewed in this paper. Current knowledge about nutritional therapy and its efficacy, goals and objectives is presented, along with recommendations used in treatment programmes. Lastly, the key steps of nutritional management are summarised.

Conditioned taste aversion induced by wheel running: further evidence on wheel running duration

Rats given access to a running wheel after drinking a flavored solution subsequently drink less of that liquid. It has been suggested that suppression of intake is the result of conditioned taste aversion (CTA). This study explored whether the magnitude of CTA is related to time in the wheel (i.e., amount of wheel running). During 4 days of conditioning, rats drank an orange liquid for 60 min. Immediately after drinking, experimental rats were transferred to running wheels for either 20 or 60 min. Control animals remained in their home cages. Following the conditioning phase, all rats received a preference test composed of the paired flavored liquid (i.e., orange solution) and water. Rats in both experimental groups (20 and 60 min) decreased their consumption of the orange flavored liquid, but no difference in CTA was found between these groups. Wheel running, whether for 20 or 60 min, suppresses the consumption of a liquid consumed immediately before wheel access. These findings are discussed in terms of discrepancies between CTA induced by wheel running and CTA induced by emetic agents.

Single-trial exercise-induced taste and odor aversion learning in humans.

In the present study, it was investigated whether humans acquire an aversion for a flavor paired with a single bout of exercise, and if so, to what degree this effect requires the experience of gastrointestinal distress. To this end, a total of 58 participants either consumed or merely tasted a specifically flavored solution directly prior to a 30 min running exercise. In both cases this led to a negative shift in subjective liking of the flavor (taste and odor) in comparison to the evaluation of another flavor not explicitly paired with exercise, indicative of a conditioned flavor aversion. The degree of subjectively experienced exercise-related gastrointestinal distress did not predict this negative hedonic shift for the flavor paired with the running exercise, implying that such distress may not be a prerequisite for exercise-induced flavor aversion learning in humans.